Author Topic: P38L High Speed Flaps (Read 773 times)

Tac · « **Reply #15 on:** October 24, 2002, 11:58:41 AM »

P-38 has dive flaps, not dive BREAKS.

Wilbus · « **Reply #16 on:** October 24, 2002, 12:08:32 PM »

Quote

Evil wilbus...just evil

Lazerr · « **Reply #17 on:** October 24, 2002, 12:56:05 PM »

Stop posting under two name dweeb!:p

viking73 · « **Reply #18 on:** October 24, 2002, 05:02:47 PM »

according to this article, the Fowler Flaps on the p-38 can be used up to 250mph. The p-38 also had an "aileron boost". Don't know if that is included in AH.

p-38

Wilbus · « **Reply #19 on:** October 24, 2002, 05:08:11 PM »

Who ya talking to Lazer?

stantond · « **Reply #20 on:** October 24, 2002, 10:26:49 PM »

From everything I have read (got references if anyone is interested... except for *you* TAC) the P38J and later combat versions were equipped with a dive brake. This was not part of the flap system but an add on. The brakes were located beside the engines on the underside of the wing (similar to what AH shows offline from an exernal view).

So, is the consensus that the high speed flaps (ie AW P38J) were not physically used? It does seem the dive brake in AH does not seem to work. Maybe that's a feature of the game?

The maximum speed before compressibility as printed was 0.67 Mach (~450 mph at sea level). For what that bit of trivia is worth. I really hope this thread is not attracting morons.

Bodhi · « **Reply #21 on:** October 24, 2002, 11:36:00 PM »

The P-38's "Dive Flaps" (or compressibility flaps per Kelly Johnson) are located in the the lower side of the Outboard Wing panels, About a foot behind the spar and approximately 1 foot out board of the wing panel joint. They are about 4 feet long, and are at their widest approxiamtely 1 foot. The work in a simple form, they are hinged in the front, and about 1/2 way back, the forward winged panel swings down and forward, while the aft remains parallel to the wings lower surface. This simple two piece flap is actuated by an ELECTRIC motor, the prototype was hydraulic. It is NOT a DIVE BRAKE, but merely a small flap that restores lift to the wing being lost to the effects of compressibilty. There are two positions, fully deployed, or fully retracted. They are to be deployed immediately upon entering a dive, or shortly there after. These "dive recovery flaps" were installed as standard equipment on the J-25 series and continued through out production. They are succeptible to failure at high speeds, and have great difficulty deploying at a high rate of speed, as the electric motor is VERY small. Lastly, the electro/hydraulic controls you are refering to, Stantond, are located in the WING FLAP Drive motors, and the Boosted Ailerons. Hope this helps, will try to remember to take some pics of some real ones tomorrow, and bring home the manual.

Bodhi · « **Reply #22 on:** October 24, 2002, 11:52:05 PM »

This is a basic view of the flap from the underside of the wing... it is just a drawing but gives an accurate placement.....

Bodhi · « **Reply #23 on:** October 25, 2002, 12:00:37 AM »

Here, found an actual photo with none other than Kelly Johson included! See, the flap is so simple, and is basically attached to the exterior of the wing... It is deployed in the photo...

gripen · « **Reply #24 on:** October 25, 2002, 06:37:47 AM »

"The Mighty Eighth War Manual" by R. Freeman contains some information about problems with the dive recovery flaps:

"The 479th Group received two aircraft with such flaps in August 1944 - at which time it was the last P-38 equipped group in VIII FC. After some hours flying with them they complained that the flaps continually broke down; one aircraft had needed repair nine times. The Group arranged to exchange these aircraft for two without flaps."

Kelsey's accident was caused by prototype version of the dive recovery flaps (hydraulic operated as Bodhi noted); the flaps failed to work when Kelsey was testing if they can be opened at high speed when compressebility effects started. Kelsey did all his tricks but could not stop "tuck under" and other wing failed. Somehow Kelsey got out of the plane.

This report contains some info about the dive recovery flaps, this page shows how "tuck under" developed and how the dive recovery flaps countered it.

gripen

stantond · « **Reply #25 on:** October 25, 2002, 07:28:27 AM »

Here is a link with some information on P38 testing:

http://oea.larc.nasa.gov/PAIS/WWII.html

The "dive recovery flaps" (what I call dive brakes per AH, AW, etc) were not what I was originally asking about. Although I am leaning towards the idea that there were no high speed flaps (such as the P51's use). It would satisfy my curiosity to see that in print though.

Some of this (obsession?) comes from Air Warrior. I was generally impressed with the detail and research of the flight models in the game. That is not to say they were 100% historically accurate. AW was, like AH, a game and some things were “embellished” to keep the players happy.

Your info is very cool BTW Bodhi.

stantond · « **Reply #26 on:** October 25, 2002, 10:33:37 PM »

OK,

Figured out how the dive flaps (what I have been calling dive brakes) work. They work similar to how historical records state. While they don't pull the nose up, they do allow the nose to be pulled up with trim.

Without the dive flaps, trim won't pull the nose up after compression. With the dive flaps, elevator trim will get the nose up. The dive flaps don't provide any enhanced manueverability or slow the plane down. They break up the air flow and allow the control surfaces to work (elevator trim at least).

Check it out (offline) and see what I am talking about.

buzkill · « **Reply #27 on:** October 26, 2002, 07:28:29 AM »

the only difference i've seen with dive flaps on p38 in AH is the way they help stabalize the plane when fighting a zeke at low alt.,low speed. suprised a few ppl with it.

TheCage · « **Reply #28 on:** October 27, 2002, 02:33:10 PM »

Well here is what I found on the 38:

The L-5 has
- different engines (but same ratings, yet some sources say that the L's engines could run WEP at 1725 HP, rather than 1600)
- landing light inset in leading edge of left wing rather than a retractable light under wing as on the J
- improved fuel system
- tail warning radar
- improved turbosuperchargers
- hard points for Christmas tree rocket launchers (standard)

The L was the definitive Lightning, and met practically all the expectations originally conceived and exceeded others not originally conceived, such as photo-reconnaissance and formation bombing.

Here's a quote by Capt. Stan Richardson:

"The P-38J25-LO and P-38L's were terrific. Roll Rate? Ha! Nothing would roll
faster. The dive recovery flaps ameliorated the "compressibility" (Mach
limitation) of earlier Lightnings. An added benefit of the dive recovery
flaps was their ability to pitch the nose 10-20 degrees "up" momentarily
when trying to out turn the Luftwaffe's best, even when using the flap
combat position on the selector. Of course the nose "pitch-up" resulted in
increased aerodynamic drag, and must be used cautiously. High speed is
generally preferred over low speed in combat situations. Properly flown, the
Fowler flaps of the P-38 allowed very tight turning radius."

viking73 · « **Reply #29 on:** October 28, 2002, 03:25:39 AM »

Standond, as far as I can tell you are asking if the flaps on the 38 work like the ones on the 51. The answer is yes but only at 250. I believe the 51's flaps work at a higher speed. There were no "speed flaps" on either plane that I know of. Just the regular flaps which activate at different speeds. On many of the American planes you can activate flaps to enhance manuevering.